‘The ability to take something like technical lignin and not only break it down and turn it into a useful product, but do it at a cost and environmental impact that is lower than petroleum materials, is something that no one has really been able to show before.’
A team of researchers from the University of Delaware, US, in collaboration with CanmetEnergy, Canada’s leading research and technology organisation in the area of clean energy, have demonstrated a cost effective process for converting industrially processed lignin into ‘high-performance plastics.’
Publishing their work in the journal Science Advances, the researchers were able to use waste lignin from the manufacture of pulp and paper, known as technical lignin, and produce bio-based 3D-printing resins as well as ‘valuable chemicals.’ Until now the lignin used by the researchers was typically burned for heating or added to tyres as fillers. The researchers point out that existing processes to upgrade lignin require very high pressures, and are hard to scale. In addition current industrial techniques have safety concerns, as well as high capital costs and energy consumption due to the types of solvents required and high temperatures.
To overcome these challenges, the researchers replaced the traditional solvent methanol, used for breaking down lignin, with glycerine, which allowed the process to be carried out at ambient pressure. Using glycerine, the researchers said, provided the same chemical functionality as methanol, but at a much lower vapour pressure eliminating the need for a closed system and allowing the reaction and separation to carried out simultaneously. Developing the process so that it was repeatable took around a year, the researchers added.
Analysis has indicated that this low-pressure method can cut the cost of producing a bio-based pressure-sensitive adhesive from softwood Kraft lignin, by up to 60%, when compared with the high-pressure process. When other types of technical lignin were used, the cost advantage was less pronounced. However softwood Kraft lignin is one of the most abundant types of technical lignin generated by the pulp and paper industry.
Commenting, Professor Thomas H Epps, III; Allan and Myra Distinguished Professor of Chemical and Biomolecular Engineering, at the University of Delaware and project leader said; ‘The ability to take something like technical lignin and not only break it down and turn it into a useful product, but do it at a cost and environmental impact that is lower than petroleum materials, is something that no one has really been able to show before.’